A Differential Fault Analysis on AES Key Schedule Using Single Fault

This work analyzes the strength of NIST Lightweight Cryptography (LWC) Round 1 Candidate SIV-Rijndael256 in light of Differential Fault Attacks (DFA). It is observed that SIV-Rijndael256 presents an interesting case for DFA due to its large state-size which has been capitalized in this work to contribute to the state-of-the-art in DFA on AES-like ciphers. We first study the differential properties over three rounds of the cipher and then use it to mount a DFA that uses a classical strategy in conjunction with the properties of the key-schedule. The nonce-misuse property of SIV-Rijndael256 facilitates the use of DFA and is exploited to reduce the key-space from 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">128</sup> to just one using only a single random byte fault in the internal state. Moreover, the support for the release of unverified plaintexts which have been shown in literature as a vulnerability to DFA, makes the decryption also vulnerable to the same attack. Finally, the ability to uniquely retrieve the key using just a single fault makes the attack, reported here, an optimal DFA. To the best of our knowledge, this is the first differential fault analysis of any candidate in the NIST LWC competition.

Differential fault analysis (DFA) finds the key of a block cipher using differential information between correct and faulty ciphertexts obtained by inducing faults during the computation of ciphertexts. Among many ciphers, advanced encryption standard (AES) has been the main target of DFA due to its popularity. The naive implementation of AES is known to be vulnerable to DFA, which can be split into two categories depending on the fault location: the DFA on the State and the DFA on the Key Schedule. For the first category, much research has been done and very efficient methods were devised. However, there is still a lack of research in the second category. The advantage of DFA on the Key Schedule is that it can even defeat some fault-protected AES implementations. Research on DFA has been diversified into several directions: reducing the number of required faults, changing fault models (from one-byte fault to multibyte fault and vise versa), extending to AES-192 and AES-256, and exploiting faults induced at an earlier round. This paper deals with all these directions together in DFA on AES Key Schedule. We introduce new attacks that find the AES-128 key with two faults in a one-byte fault model without exhaustive search and the AES-192 and the AES-256 keys with six and four faults, respectively.

Basically, Differential Fault Analysis (DFA) against ciphers consists of two stages: fault induction and fault exploitation. Success rate of the latter strongly depends upon the availability of the required type of some faulty ciphertexts, which typically assumes that adversaries have precise control over the location, timing and/or even the type of the fault induced. In view of this, there seems to be a technical gap between these two stages. In this paper, by amplifying the fault propagation pattern inherent in block ciphers, we propose an algorithmic method to narrow this gap, or to relax the underlying assumption. Our method provides a faulty ciphertext filtering process between two basic stages in DFA. This additional process equips adversaries with the capabilities to deterministically decide whether or not one faulty ciphertext is relevant to a specific DFA, before or without performing DFA itself. We take AES as a concrete case of study and conduct theoretical analysis and simulation experiments as well, the results of which strongly demonstrate the validity and power of our proposed filtering method.

Differential fault analysis on the contracting UFN structure, with application to SMS4 and MacGuffin

Stream ciphers are highly frequent in the realm of secret key cryptography because of their low-computational complexity and latency. Though variety of attack models for testing the robustness of various stream ciphers are available, the differential fault analysis (DFA) model is the most popular. DFA is used not only to disclose the identity of any unknown cipher but also to recover the secret KEY and the cipher’s internal state. Deep learning approaches extract patterns from large amounts of cryptographic data, which aids in crypt-analysis. Here, single bit and multi-bit faults are injected into the internal register of trivium cipher, and artificial neural network (ANN) is used to identify the injected fault location without any handcrafted features of keystream unlike other existing state-of-the-art fault analysis techniques. In order to enhance the speed of fault analysis, we have used system on chip (SoC) platform where ANN-based classifier has been placed in the programmable logic area as an accelerator. This enhances the speed of fault analysis by 9% for single bit fault, 12% for two adjacent bit faults, and 13% for three adjacent bit faults compared to their software models. To the best of the author’s knowledge, this is the first of kind research where ANN-based hardware accelerator has been used for fault location identification on SoC platform.

This paper proposes a fault analysis technique on LED by combining algebraic cryptanalysis and differential fault analysis (DFA). The technique is called algebraic differential fault analysis (ADFA). In ADFA on LED, we use DFA to deduce the possible fault differences of the correct and faulty S-Box input in the last round, and convert them into algebraic equations. We then combine the equation set of LED with the injected fault and use the CryptoMiniSat solver to recover the secret key. Our experiments show that, on a common PC, ADFA can succeed on LED under the nibble-based fault model within three minutes and with only one fault injection, which is more efficient than previous DFA work. To evaluate DFA on LED, we first propose an improved evaluation algorithm of DFA, then provide a modified ADFA approach to compute the solutions for the secret key. The results are more accurate than previous work. We also successfully extend ADFA on LED to other fault models using a single fault injection, where traditional DFAs are difficult to launch.

While modern masking schemes provide provable security against passive side-channel analysis (SCA), such as power analysis, single faults can be employed to recover the secret key of ciphers even in masked implementations. In this paper, we propose random space masking (RS-Mask) as a countermeasure against both power analysis and statistical fault analysis (SFA) techniques. In the RS-Mask scheme, the distribution of all sensitive variables, faulty and/or correct values is uniform, and it therefore protects the implementations against any SFA technique that exploits the distribution of intermediate variables, including fault sensitivity analysis (FSA), statistical ineffective fault analysis (SIFA) and fault intensity map analysis (FIMA). We implement RS-Mask on AES, and show that a SIFA attack is not able to identify the correct key. We additionally show that an FPGA implementation of AES, protected with RS-Mask, is resistant to power analysis SCA using Welch's t-test. The area of the RSMasked AES is about 3.5 times that of an unprotected AES implementation of similar architecture, and about 2 times that of a known FPGA SCA-resistant AES implementation. Finally, we introduce infective RS-Mask that provides security against differential techniques, such as differential fault analysis (DFA) and differential fault intensity analysis (DFIA), with a slight increase in overhead.

Differential fault analysis (DFA) was introduced by Biham and Shamir. It is a powerful analysis technique to retrieve the secret key by injecting fault into an internal state and utilizing the differences between the correct ciphertexts and the faulty ciphertexts. Based on the idea of meet-in-the-middle, some differential characters can help to recover the key of some symmetric ciphers. At CHES 2011, this technique was utilized to give analyses on AES. In this article, we propose several DFA schemes on ITUbee, a software-oriented block symmetric cipher for resource-constrained devices based on the meet-in-the-middle idea. Our attacks are efficient enough and more powerful than previous works. Furthermore, the attacks in this article break the protection countermeasure, meaning we have to review the protection method on devices for ITUbee.

In this paper we present an improved differential fault attack on the Advanced Encryption Standard (AES) with 256-bit key. We show an improved attack which retrieves the AES-256 key using two pairs of fault free and faulty ciphertexts and a brute-force search of 216 with a time complexity 232. The attack retrieves the secret key within approximately 45 minutes, running on desktop Intel Core TM 2 Duo processor of 3GHz speed. To the best of the knowledge of the authors, this is the most optimized fault attack on AES-256 among reported results requiring only two faulty ciphertexts.

Side channel analysis(SCA) focuses on attacking cryptographic algorithm implementations by collecting leaked information and analyzing the correlation between the leaked and key information in the cryptographic system. Currently, SCA is the main threat to cryptographic implementations, with DPA (differential power analysis) and DFA (differential fault analysis) being two of the most threatening types of SCA. However, the existing countermeasures against DPA and DFA have shortcomings and can hardly protect cipher designs perfectly. Based on a comprehensive analysis of DPA and DFA, this paper proposes a new idea of using an evolutionary cipher (EVOC) against DPAs based on the model proposed by Kocher, and several different new types of DFAs. In fact, an EVOC is a kind of dynamic cipher designing method. Moreover, combined with intelligent searching algorithms and cryptography design policies, EVOCs utilize the dynamic and unpredictable properties of TRNG (a truly random number generator) to ensure cipher design at a high level of security. Therefore, with an EVOC we could design cryptography algorithms with high security to resist mathematical analysis as well as DPAs and DFAs. This paper analyzes and proves the security, efficiency, cost, and original features of EVOCs against DPA and DFA both theoretically and experimentally. Compared with existing countermeasures against SCAs, EVOCs use dynamic non-linear operations to destroy the bases of DPA and DFA. At the algorithm level, EVOCs are more efficient than other resistance methods. Based on the theory and experiments, this paper proposes certain modifications to the EVOC in the AES (advanced encryption standard) algorithm, which can be referenced by other dynamic designs of cryptographic algorithms.

In 2013, the US National Security Agency proposed two new families of lightweight block ciphers: SIMON and SPECK. Currently, linear and differential cryptanalytic results for SIMON are available in the literature but no fault attacks have been reported so far on these two cipher families. In this paper, we show that these families of ciphers are vulnerable to differential fault attacks. Specifically, we demonstrate two fault attacks on SIMON and one fault attack on SPECK. The first attack on SIMON assumes a bit-flip fault model and recovers the n-bit last round key of SIMON using n/2 bit faults. The second attack on SIMON uses a more practical, random byte fault model and requires n/8 faults on average to retrieve the last round key. The attack presented on SPECK also assumes a bit-flip fault model and recovers the n-bit last round key of SPECK using n/3 bit faults on average.

In the 1970s researchers noticed that radioactive particles produced by elements naturally present in packaging material could cause bits to flip in sensitive areas of electronic chips. Research into the effect of cosmic rays on semiconductors, an area of particular interest in the aerospace industry, led to methods of hardening electronic devices designed for harsh environments. Ultimately various mechanisms for fault creation and propagation were discovered, and in particular it was noted that many cryptographic algorithms succumb to so-called fault attacks. Preventing fault attacks without sacrificing performance is nontrivial and this is the subject of this book. Part I deals with side-channel analysis and its relevance to fault attacks. The chapters in Part II cover fault analysis in secret key cryptography, with chapters on block ciphers, fault analysis of DES and AES, countermeasures for symmetric-key ciphers, and countermeasures against attacks on AES. Part III deals with fault analysis in public key cryptography, with chapters dedicated to classical RSA and RSA-CRT implementations, elliptic curve cryptosystems and countermeasures using fault detection, devices resilient to fault injection attacks, lattice-based fault attacks on signatures, and fault attacks on pairing-based cryptography. Part IV examines fault attacks on stream ciphers and how faults interact with countermeasures used to prevent power analysis attacks. Finally, Part V contains chapters that explain how fault attacks are implemented, with chapters on fault injection technologies for microprocessors, and fault injection and key retrieval experiments on a widely used evaluation board. This is the first book on this topic and will be of interest to researchers and practitioners engaged with cryptographic engineering.

Differential fault analysis (DFA) has already been applied to attack many block ciphers with the help of inducing some faults at the last few rounds of block ciphers. Currently, a general countermeasure against DFA is to protect the last few rounds of block ciphers by means of redundancy. In this paper, we present a new fault attack on block ciphers called linear fault analysis (LFA), in which linear characteristics for some consecutive rounds of a block cipher will be utilized instead of exploiting differential distributions of S-Boxes within the block cipher in DFA. Basically, the new approach can handle the case that faults are induced several rounds earlier compared to DFA, thus leading to a threat to the protected implementations (against DFA) of block ciphers. For the purpose of illustration, we mount an effective attack on SERPENT by adopting LFA and achieve a good cryptanalytic result on SERPENT. We hope that our work enriches the picture on the applicability of fault attacks to block ciphers and could be beneficial to the security evaluation of block ciphers.

In recent years, many lightweight block ciphers were proposed to provide security for resource‐constrained environments such as Internet of Things (IoT). PIPO, which stands for “plug‐in plug‐out”, is just a lightweight bit‐sliced block cipher offering excellent performance in 8‐bit AVR software implementations. In fact, PIPO owns 64‐bit input and output, 128‐bit secret key. In this article, we consider the differential fault analysis (DFA), a typical side‐channel attack, on the PIPO cipher. More concretely, for the first time, we apply the mixed attack model, which considers the DFA on the encryption state and key schedule simultaneously, to recover PIPO's 128‐bit master key. The theoretical analysis shows that, in average, after injecting 4‐byte faults, the complexity of obtaining the master key reduces from 2128 reduces to 214. In fact, this attack model alleviates the assumption on attacker than the bit‐injection case. It should be noted that our analysis also holds for other bit‐sliced block ciphers. Finally, the simulations show that our proposed DFA on PIPO cipher is rather practical.

This paper presents a practical Differential Fault Analysis (DFA) method for the iterative operation on the SubBytes transformation AES. To inject a fault to the iterative operation, we conduct an experiment using a laser injection tool. And, then to deduce the last round key, we analyze the relationship between the input of S-Box and the output of S-Box. Based on a computer analysis, our proposal fault attack retrieves the AES 128-bit secret key with about 211 complexity in average using one pair of correct and faulty ciphertext.